brushless motor/sanjeet-1308143
TRANSCRIPT
Brushless Dc motor
Presented by:Sanjeet kumar
Registration No.-1308143Branch: Electrical & Electronics Engineering
Brushless Dc Motor• Brushless DC Motors are a type of
synchronous motor. magnetic fields generated by the stator and rotor
rotate at the same frequency no slip Has no brushes and commutators. Rotation of the rotor depends on the accurate
position with stator.
• Detected by Hall Sensor, mounted on rotor, shifted at 60º or 120º phase shift.
• Electronic commutation used to vary the PWM duty-cycle for speed control, using software.
• Available in single-phase, 2-phase, and 3-phase configurations
BLDC Motor Stator
BLDC Motor Rotors
Working of Brushless dc motor As there is no commutator ,the
current direction of the conductor on the stator controlled electronically.
Rotor consists the permanent magnet where as stator consist a no. of windings. Current through these winding produces magnetic field and force.
Hall sensor used to determine the position during commutation.
Commutation of BLDCM…
Brushless DC motor requires external commutation circuit to rotate the rotor.
Rotor position is very important.
HALL SENSOR senses the position of the coil accurately.
Working Procedure• When electric current passes through a coil in a magnetic field, the magnetic force produces a
torque which turns the motor.
• Force in Motor:• F=ILB• F = Force • B = Magnetic Field• L = Length of Conductor• I = Current in Conductor
• Torque in Motor:• T = IBA sin θ• A = LW• L = Length of Winding• W = Width of Winding
Hall-Effect
• If a current-carrying conductor is kept in a magnetic field, the magnetic field exerts a force on the moving charge carriers, tending to push them to one side of the conductor, producing a measurable voltage difference between the two sides of the conductor.
Hall-Effect Sensors
• Need 3 sensors to determine the position of the rotor
• When a rotor pole passes a Hall-Effect sensor, get a high or low signal, indicating that a North or South pole
Transverse Sectional View of Rotor
Commutation Sequence
• Each sequence has one winding energized positive (current into the
winding) one winding energized negative (current out of the
winding) one winding non-energized
Torque-Speed Characteristic
Advantage In BLDC motor PM are on the rotor &
electromagnets are on the stator controlled by software. Thus the advantages are:
1. Because of computer control it is more precise & more efficient.
2. There is no sparking & less electrical noise.
3. Voltage and current rating is high.4. High speed can be achieved.5. As there is no brushes it requires no
servicing.6. It has longer life.7. Low Radio Frequency Interference and
electromagnetic Interference.
Disadvantage
Requires Complex Drive Circuitry. Requires additional Sensors. Expensive. Some designs require manual labor.
(Hand wound Stator Coils)
Applications• PMBLDC motors are increasingly
being used in a wide spectrum of applications:
• domestic equipments,• automobiles• information technology equipment• industries• public life appliances • transportation• aerospace, defence equipments, power
tools, toys, vision and sound equipments • medical and health care equipment
ranging from microwatts to megawatts.
